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We are designing a product which needs to provide data and power to an SSD connected using SATA. However, we cannot find a specification of the power requirements for a SATA connector. How much power should a power supply behind a SATA power connector provide at a minimum?

I have acccess to the SATA specification. However, we did not find a specification of a minimum power supply. It only mentions the 1.5 A rating of the individual pins. It seems to define how to deliver power, but not how much.

I found an answer on power connector pins and the wikipedia entry on SATA power connectors. However, it seems to me that the 1.5 A specified there is the minimum the connector should support. That is, the connector should not melt if I put 1.5 A per pin through it. I don't think it means the SATA device connected to it can expect 1.5 A per pin to be supplied.

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As @bitshift says, you'll likely need to get the actual spec to be sure.

1.5A may well be a real supply requirement, though. The cables used are actually rated to 4.5A per supply rail. The connectors contain 3.3V, 5V, and 12V rails.

A regular (magnetic 3.5") hard drive can dissipate almost 10W. This energy is probably split across the three available power rails. Since I have no idea what the split may be, the worst case numbers look something like this :

All 10W @ 3.3V - 3.33A
All 10W @ 5V   - 2A
All 10W @ 12V  - 0.83A

The actual spec could help you understand how the load is allowed to be spread over the three supplies and what the effective ratings needed are.

If you don't care about it being SATA compliant, you could assume the load is lower by a factor of 2 or so since you're only using SSDs.

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  • \$\begingroup\$ I don't think 3.3 V is required by any drive (many cables actually lack a 3.3V wire) and IIRC it only has two pins (the third has been repurposed for power disable). \$\endgroup\$
    – Oskar Skog
    Jun 19, 2020 at 22:20
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1.5A per pin is the design spec, though in practice you'd de-rate it. The MOLEX specification for the connector is just that, and is agnostic to what you should run where.

For power requirements look at the ATX specification. The SSD is expecting the pin-out, voltage, and ripple to be within the ATX specification. So long as you meet it when the SSD is going full out. I don't think there's a standard minimum per connector, as there are a lot of embedded low Wattage DC power supplies that are ATX rated.

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    \$\begingroup\$ You do realize you've answered a question from 3-1/2 years ago? Don't worry, a lot of us have done that too. \$\endgroup\$
    – SteveSh
    Jan 18, 2020 at 20:41
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    \$\begingroup\$ I do, I was just going to comment, but then I started writing more than was reasonable to put in a comment. \$\endgroup\$
    – WorBlux
    Jan 22, 2020 at 1:43
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It looks like to get a definitive answer you may need to purchase the spec from The Serial ATA International Organization. If not, getting in touch with them may be valuable anyway.

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  • \$\begingroup\$ My apologies, I did not mention that I do have access to the SATA specification. However, it does not seem to specify a minimum power requirement. I will adapt the question accordingly. \$\endgroup\$
    – KiekerJan
    Jul 14, 2016 at 8:13

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